1. Field of the Invention
This invention concerns catheters to be implanted inside a patient's body to perform infusion, and more specifically an externalized sealed catheter with leakproof access.
2. Description of Prior Art
Catheters have long existed that can be implanted under a patient's skin, with entry through an access site. The latter is generally in the form of a rigid chamber with a septum just under the patient's skin. To perform a infusion on a patient undergoing periodic chemotherapy, the physician or nurse locates the septum by palpation to insert the infusion needle. The septum is made of material easily penetrated by the infusion needle, but becomes leakproof once again after the needle is withdrawn. Generally, the septum must be replaced after a certain number of infusions, usually several hundred, since it is weakened by the large number of infusions and loses its leakproofness.
Implantation of the septum under the skin may have several disadvantages. Thus, a defect in leakproofness of the septum or displacement of the infusion needle during infusion may cause leakage under the skin. The use of aggressive medication in the infusion product can also be dangerous for the patient because the needle punctures the skin.
There are externalized catheters with one open extremity. They are generally closed by a rigid removable stopper. This stopper is not a septum and cannot be punctured by an infusion needle. At the time of infusion, the stopper is removed and the catheter connected to the source of infusion liquid, using a `cone luer lock`-type needleless syringe for instance as described in patent EP-A-266.243. Such so-called `open` systems often result in infection because entry to the catheter is exposed to the air every time infusion is performed.
There are also externalized catheters like that described in patent EP-A-143,518, with the extremity external to the patient closed by a septum. But this septum sealing the catheter is of the pre-existing aperture type so the therapeutic solution can be perfused through a cannula, rather than a needle, as is the case with a self-repairing septum. Unlike the self-repairing septum, this type of septum with a pre-existing aperture cannot be used repeatedly without enlarging the aperture, thereby connecting the catheter with the outside and all the dangers of infection.